Biomedical subjects

F Philippe

Publications and source records attributed to F Philippe.

At least 37 records · Page 2Linked to original sources

PubMed2000

Effects of various anticoagulant treatments on von Willebrand factor release in unstable angina.

OBJECTIVES: We tested the hypothesis that different anticoagulant treatments may produce different platelet effects and von Willebrand factor (vWf) release in unstable angina. BACKGROUND: The early increase of vWf has been reported to be a risk factor for adverse outcome in unstable angina. Anticoagulant drugs play a key role in stabilization of unstable angina, but they may not have the same efficacy and the same effects on acute vWf release. METHODS: We studied 154 patients enrolled in several clinical trials testing four different anticoagulant treatments in unstable angina or non-Q-wave myocardial infarction. Patients were treated during at least 48 h by either intravenous unfractionated heparin, one of two different low molecular weight heparins (enoxaparin or dalteparin) or the direct thrombin inhibitor PEG-hirudin. All patients received aspirin but no Ib/IIIa inhibitors. RESULTS: The release of vWf over the first 48 h (delta vWf) did not relate to the baseline clinical characteristics. At 30 days of follow-up, delta vWf was sevenfold higher in patients with an end point (death, myocardial infarction, revascularization) than in patients free of events (+53 +/-7% vs. +7 +/-14%, p = 0.004). The same trend was present for each component of the composite end point with the highest levels for one-month mortality (+87 +/- 32% vs. +26 +/- 8%, p = 0.09). The vWf values did not increase over 48 h in patients receiving either enoxaparin or PEG-hirudin (+10 +/- 9% and -5 +/- 20%, respectively). A serious rise ofvWf was measured in unfractionated heparin-treated patients (+87 +/- 11%), which differed significantly from the enoxaparin group (p = 0.0006) and PEG-hirudin group (p < 0.0001). In dalteparin-treated patients, delta vWf was elevated (+48 +/- 8%) and did not differ from the unfractionated heparin group (NS). CONCLUSIONS: We confirm that, in unstable angina patients, a rise of vWf over the first 48 h is associated with an impaired outcome at 30 days. Moreover, the four different anticoagulant treatments tested here do not provide the same protection with regards to vWf release, which may have important prognostic implications and explain different results observed in recent clinical trials.

Aged↗

PubMed2000

[Echocardiographic diagnosis of left intraventricular thrombi: contribution of high frequency probes].

Two-dimensional echocardiography is the reference technique for the diagnosis of left ventricular thrombi. However, it has some limitations due to poor imaging of the apex; location of many thrombi. Apical resolution improvement is possible using a 5 MHz ultrasonic transducer, which may identify 3.5MHz ultrasonic transducer false positive results. In a series of 53 patients with left ventricular dysfunction, we detected 11 thrombi. Using the 5MHz ultrasonic transducer as a reference the sensitivity of the 3.5MHz ultrasonic transducer was 100%, and much greater than that of the 2.5MHz ultrasonic transducer (55%), which was associated with 4 false positive results. The increased sensitivity associated with transducers of higher frequency was however limited by the echogenicity of patients, all the more since we used a medium instead of a short focalisation. Due to its therapeutic consequences, the detection of left ventricular thrombi must be enhanced using 5 MHz ultrasonic transducer, all the more in echogenic patients.

Echocardiography↗

PubMed2000

[Iatrogenic dissection of the left main artery treated by direct stenting].

A 70-year-old woman was referred to the department due to a symptomatic severe calcific-aortic stenosis. During pre-operative trans-radial approach coronagraphy occurred a iatrogenic dissection of the left main artery with total occlusion and cardiac arrest (asystole). Successful resuscitation is achieved with an emergency strategy of percutaneous direct stenting revascularization combined with cardiopulmonary resuscitation manoeuvres.

Aged↗

PubMed2000

[Coronary subclavian steal syndrome after internal mammary artery bypass grafting. A cause of severe postoperative recurrent myocardial ischemia].

A 65-year-old underwent a triple bypass: internal artery mammary-descending coronary artery, aorta diagonal-lateral coronary (sequential). Three weeks later he started to have severe angina pectoris with ST depression in anterior EKG leads. A left transradial coronary angiography was performed. The examination showed a total occlusion of the left subclavian artery 2 cm after the aortic arch and a retrograde flow in the internal mammary artery (IMA). Via transfemoral approach, angiography showed the patency of the aorto-veinous sequential graft and a retrograde flow through anastomosis in the left mammary artery. The patient underwent a reimplantation of the IMA on the brachiocephalic artery. One month later the patient is doing well without chest pain. A coronary subclavian steal syndrome should be suspected in case of recurrent ischaemia after IMA bypass, particularly if there is more than 20 mmHg systolic pressure differential between the arms. Left transradial approach achieved diagnostic in case of total left subclavian artery occlusion.

Aged↗

PubMed1999

Reliability of the current models of instantaneous pollutant emissions

Pollutant emissions and fuel consumption of passenger cars are usually assessed as a function of average as a function of average speed. Nevertheless a number of attempts were made to take into account the driving pattern using emission vs. instantaneous speed and acceleration models. Five quite similar models were developed in Europe. To which extent these instantaneous models are innovative as compared to conventional models? In a first step the various development stages of an emission-based model and the various associated errors are presented. Among the possible sources of error, we selected modelling-induced errors, enabling to compare rigorously the various model types in terms of performance. The analysis was performed using the Modem model, developed from the measurement results obtained over a sample of 150 vehicles, representative of French, English and German fleets, over 14 representative driving cycles under urban conditions. Average emissions as measured over these 14 cycles are compared to emissions calculated over same cycles using this model. Modelling errors range from -51% to +57% as a function of the considered cycle and the vehicle type. This inaccuracy is quite similar for the other four European models. This demonstrates the low reliability of the models used, which cannot be used to assess the impact of slight changes in the driving pattern, sometimes leading to completely false conclusions. These models are barely more precise than average speed based models. In a second step, a number of alternatives liable to improve the reliability of instantaneous models are contemplated: for example using another method for calculating acceleration, or increasing the number of speed and acceleration classes significantly. But this does not improve significantly the model reliability. Limited measurements performed on a catalyst vehicle demonstrated that very high engine loads, even if not frequent, play a significant role in emissions: sometimes they yield emission values a thousand times higher. It is therefore of prime interest to study them in a comprehensive manner. In addition, this demonstrates that each model should be developed from measurements carried out over a set of representative driving cycles under real-world driving conditions.

Journal Article↗

PubMed1999

[Harvesting of an internal saphenous graft for aorto-coronary bypass using video-surgery].

Classical excision of saphenous vein grafts requires a continuous incision on the leg or the thigh or both. To minimise the trauma due to this method, an endoscopic method has been recently developed. The aim of this paper was to assess the benefits of this new method compared with the classical technique. One hundred and twenty patients requiring aorto-coronary grafts were included in this prospective study and divided into two groups according to the method of saphenous vein harvesting. Group A comprised 60 patients who underwent the classical method os saphenous vein harvesting and Group B 60 patients who benefited from the endoscopic method. No difference was observed between the two groups with respect to mean age, sex ratio, history of diabetes and obliterative arterial disease of the lower limbs. Parsonnet index number of bypass grafts and length of vein excised. The length of the skin wound in group A was 30.8 +/- 8.5 cm compared with only 4.1 +/- 1 cm in Group B (p = 0.006) but the harvesting time was longer by endoscopy (55.7 +/- 23.7 minutes: 72.5 +/- 22.6 minutes for the first 10 patients, 48.5 +/- 24.7 minutes for the last 50 patients) compared with the classical technique (39.8 +/- 6.6 minutes: p = 0.001). Moreover, patients who underwent videosurgery had less operative pain (8% versus 15%) (p = 0.001). The number of infectious complications was slightly lower in Group B (3.3%, 2/60, versus 10%, 6/60), (NS). The authors conclude that harvesting of the saphenous vein by videosurgery reduces postoperative pain and gives a more aesthetic result but with a slightly longer operative time at the beginning of the experience.

Adult↗

PubMed1999

[Myocardial infarction after a stress test. A case report].

The authors report a case of first myocardial infarction occuring after an asymptomatic stress test in a patient presenting several cardiovascular risk factors. Coronary angiography, performed before the 4th hour after onset of the symptoms in this patient, identified the mechanism of myocardial infarction to be occlusion of the left anterior descending artery by thrombus, very probably complicating rupture of an atherosclerotic plaque. The initial failure of thrombolytic therapy led to a mechanical revascularization procedure with primary success. The pathophysiological mechanisms possibly contributing to this type of accident are discussed.

Angioplasty, Balloon, Coronary↗

PubMed1998

Effects of prostacyclin on the pulmonary vascular tone and cardiac contractility of patients with pulmonary hypertension secondary to end-stage heart failure.

Long-term administration of prostacyclin (PGI2) improves the hemodynamic state, symptoms, and survival in patients with primary pulmonary hypertension, but it increases mortality in patients with heart failure despite obvious hemodynamic benefits when it is given acutely. We evaluated the mechanisms of action of PGI2 in patients with heart failure and secondary pulmonary hypertension. Nineteen patients with end-stage heart failure and pulmonary hypertension, all candidates for heart transplantation, underwent right- and left sided cardiac catheterization with micromanometer-tipped catheters and were tested for PGI2 at incremental doses. PGI2 infusion significantly improved pulmonary hemodynamics with a 47% reduction in pulmonary vascular resistance (p=0.0003) and a doubling of pulmonary artery compliance (p <0.0001), reflecting improvement in pulmonary vascular tone. The dose of PGI2 necessary to reach this hemodynamic effect correlated significantly to the baseline severity of pulmonary artery compliance (r=0.54, p=0.01). Furthermore, PGI2 produced a significant positive inotropic effect (contractile element maximum velocity increased from 1.10+/-0.09 to 1.33+/-0.13 circ/s, p <0.009). The hemodynamic effects of PGI2 infusion were independent of the plasma and urinary levels of endogen prostaglandins. Thus, PGI2 at therapeutic doses exerts a positive inotropic effect in patients with heart failure, which may explain the increased mortality rate observed with the long-term use of PGI2 in this type of patient. The spectacular acute benefits on right ventricular afterload, however, may be useful in unstable patients with heart failure and secondary pulmonary hypertension or in transplanted patients with acute right ventricular failure of the donor heart.

Antihypertensive Agents↗

PubMed1998

Early increase of von Willebrand factor predicts adverse outcome in unstable coronary artery disease: beneficial effects of enoxaparin. French Investigators of the ESSENCE Trial.

BACKGROUND: The pathogenesis of unstable angina and non-Q-wave myocardial infarction is still poorly understood, and early evaluation of prognosis remains difficult. We therefore studied the predictive value of 5 biological indicators of inflammation, thrombogenesis, vasoconstriction, and myocardial necrosis, and we examined the effects of enoxaparin and unfractionated heparin on these markers after 48 hours of treatment. METHODS AND RESULTS: Sixty-eight patients with unstable angina or non-Q-wave myocardial infarction randomized in the international ESSENCE trial participated in this French substudy. C-reactive protein, fibrinogen, von Willebrand factor antigen, endothelin-1 and troponin I were measured on admission and 48 hours later. The composite end point of death, myocardial infarction, recurrent angina, or revascularization was significantly lower at 14 and 30 days of follow-up in patients allocated to enoxaparin compared with unfractionated heparin. All acute-phase reactant proteins were elevated on admission and increased further at 48 hours. Multivariate analysis demonstrated that the rise of von Willebrand factor over 48 hours was a significant and independent predictor of the composite end point at both 14 days and 30 days. Moreover the early increase of von Willebrand factor was more frequent and more severe with unfractionated heparin than with enoxaparin (mean change was +8.7+/-8.8% with enoxaparin versus +93.9+/-11.7% with unfractionated heparin, P<0.0001). The other clinical and biological variables did not predict outcome. CONCLUSIONS: In patients with unstable angina or non-Q-wave myocardial infarction, the acute-phase proteins increase over the first 2 days despite medical treatment. The early rise of von Willebrand factor is an independent predictor of adverse clinical outcome at 14 days and at 30 days. Enoxaparin provides protection as evidenced by the reduced release of von Willebrand factor, which represents a favorable prognostic finding.

Aged↗

PubMed1998

[Aorto-coronary bypass].

OBJECTIVES: Saphenous grafts used for coronary artery bypass are classically dissected via a continuous incision of the leg, the thigh or both. Recently, a new video-surgery technique has been introduced in an attempt to reduce the trauma of saphenous vein dissection. The aim of this work was to evaluate the possible benefits of this new technique compared with classical dissection. PATIENTS AND METHODS: Sixty patients requiring coronary artery bypass grafts were included in this study and randomly divided into two groups. In group I (30 patients) the saphenous vein was dissected according to the classical technique. The video-surgery technique was used for the other 30 patients in group II. The two groups were not significantly different for mean age, sex ratio, or history of diabetes or lower limb arteriopathy. The same number of bypasses was performed in both groups (2.6 +/- 0.7). Outcome was compared for: dissection related complications (hematomas, infections), length of the skin incision over the length of the dissected vein, duration of the dissection procedure, and post-operative pain. RESULTS: A leg incision was used in 28 cases out of 30 cases in both groups. The length of the saphenous vein dissected was 27.6 cm in group I and 21.8 cm in group II. The length of the skin incision was 27 cm in group I and only 4.7 cm in the video-surgery group II, giving an incision/vein ratio of 97% and 21% respectively. Operative time was however 37.9 min for group I and 48.5 min for group II. There was no significant difference between the groups for hematoma formation or infection but the patients in the video-surgery group experienced less post-operative pain. CONCLUSION: Besides an improvement in the esthetic result, video-surgery dissection of the saphenous vein reduces post-operative pain at the cost of a slightly longer operative procedure.

Aged↗

PubMed1998

[Coronary surgery without extracorporeal circulation. Indications, methods and results. Apropos of 224 cases].

Coronary revascularization without cardiopulmonary bypass is evolving as an important technique. From January 1988 to September 1997, 224 patients underwent consecutively coronary artery bypass grafting without cardiopulmonary bypass in our institution. Indications for this type of revascularization were essentially: patients with a single coronary lesion and patients which presented an increased risk for extra-corporeal circulation. Follow-up was complete. The majority of patients were men (176) and the median age was 62 years. Most patients were in CCS III and IV (79%). Unstable angina was found in 19%, 4% had a recent trans mural infarction (< or = 48 hr), and 36% had an older infarct (> 48 hr). 8% were operated in emergency, 29% presented a restenosis following angioplasty, with 4% having a complication from angioplasty, and 0.8% were operated in cardiogenic shock. Redo surgery was seen in 4% of patients. 12% of patients had an ejection fraction less than 30%, 47% an ejection fraction between 30 et 49%, and 40% patients an ejection fraction greater than 50%. Mean Parsonnet score was 10. 185 patients (82.5%) underwent single bypass, and 39 patients (17%) multiple bypasses. Ten patients (4.4%) underwent hybrid revascularization with primarily surgical grafting followed by angioplasty. Postoperative outcome included: myocardial infarction in 16 patients (7.1%), 8 patients (3.5%) were reoperated for tamponade or bleeding, 2 patients (0.8%) developed a mediastinitis, and 1 patient (0.4%) had a neurological event. Hospital mortality was 4% (9 patients). Univariate and multivariate analysis identified two risks factors: age greater than 70 (OR 4.2, CI 1-18.4), and an ejection fraction less than 30% (OR 5, CI 1.2-21.6). Survival was 99.1% at 1 year, 94% at 3 years and 83.2% at 7 years. Post operative angina occurred in 33 patients, linked to a coronary anastomosis dysfunction in 9 patients (4.1%). A significant reduction of cost was found, compared to patients operated with extra-corporeal circulation. We conclude that coronary revascularization without cardiopulmonary bypass can provide satisfactory results, for patients with single coronary lesion, or for patients with an increased risk and multiple coronary lesions.

Aged↗

PubMed1997

Plasma homocysteine and the extent of atherosclerosis in patients with coronary artery disease.

Homocysteine is a graded risk factor for the incidence of stroke and for the degree of carotid atherosclerosis. Homocysteine is also a graded risk factor for the incidence of myocardial infarction but we do not know its precise relations to the severity of atherosclerosis in coronary patients. Seventy five symptomatic coronary patients were recruited for the study. Fifty of these patients had coronary artery disease only and were compared in a case-control manner to 50 healthy controls matched for age and sex. The 25 other coronary patients had also symptoms in another atherosclerotic territory (cerebral, peripheral or both) and were also compared to 25 matched controls. Mean plasma homocysteine level was significantly higher in coronary patients than in controls (11.7 +/- 0.7 mumol l-1, n = 50 versus 9.9 +/- 0.5 mumol l-1, n = 50, p < 0.05). Homocysteine in patients with symptomatic atherosclerosis in two or three arterial sites was 15.7 +/- 1.5 mumol l-1 which differed significantly from matched controls and from patients with coronary artery disease only (p = 0.01). The extent of coronary atherosclerosis evaluated by an angiographic coronary score correlated weakly to plasma homocysteine levels (r = 0.25, p < 0.05). The patients with both hypertension and high levels of homocysteine (> 11.3 mumol l-1, median value) had more severe coronary atherosclerosis (coronary score of 16.3 +/- 2.3 versus 11.9 +/- 0.9, p < 0.05) and more diffuse atherosclerosis (number of atherosclerotic territories of 1.5 +/- 0.2 versus 1.2 +/- 0.7, p = 0.08) than the coronary patients without this association. There were no other high risk association when considering the other classical risk factors. Thus, the highest levels of homocysteine were present in patients with coronary disease and another symptomatic localisation of atherosclerosis. A small gradient in the extent of coronary atherosclerosis was found with increasing levels of homocysteine. The presence of both hypertension and hyperhomocysteinemia was associated with more severe coronary atherosclerosis.

Biomarkers↗

PubMed1997

Neuromuscular blockade with acute respiratory failure in a patient receiving cibenzoline.

Cibenzoline is a class Ic antiarrhythmic agent that can be used to treat supraventricular arrhythmias. A case is reported of cibenzoline overdose in a patient with impaired renal function, leading not only to the usual cardiac and metabolic symptoms (bradycardia and hypoglycaemia), but also to a myastheniform syndrome with acute respiratory failure. Neuromuscular blockade was demonstrated by repetitive supramaximal stimulation of the median nerve, and diaphragmatic involvement was evidenced by applying the same protocol to the phrenic nerve. Muscle strength recovered as serum cibenzoline levels decreased, allowing the patient to be weaned from the ventilator. This observation suggests that cibenzoline, like other antiarrhythmic agents, can be responsible for neuromuscular blockade, and should therefore be used with caution in patients with neuromuscular and respiratory diseases or with impaired renal function.

Acute Disease↗

PubMed1997

[Echocardiographic diagnosis of left intraventricular thrombus. A comparative study of 2.5, 3.5 and 5 MHz transducers].

The authors undertook a prospective and comparative echocardiographic study of 2.5, 3.5 and 5 MHz ultrasonic transducers for the detection of left ventricular mural thrombosis in 53 patients with left ventricular dysfunction. Thirty-three patients had advanced ischaemic heart disease following anterior myocardial infarction and 20 had dilated cardiomyopathy with a left ventricular ejection fraction of < or = 40%. Eighty-two per cent of patients had anticoagulant therapy. The diagnosis of thrombosis was based on Asinger's classification. Eleven thrombi were detected, an incidence of 21%. Using the 5 MHz transducer as a reference, the sensitivity of the 3.5 MHz transducer was 100% and much greater than that of the 2.5 MHz transducer (55%) which was associated with 4 false positive results. The specificities were respectively 97 and 86% for the 3.5 and 2.5 MHz transducers. There was no correlation between the apical Doppler flow velocities and the presence of mural thrombosis. Atrial fibrillation was significantly associated with mural thrombosis (p = 0.04). The increased sensitivity associated with transducers of higher frequency is, however, limited by the echogenicity of patients. The introduction of transducers of variable frequencies should facilitate the diagnosis and improve the sensitivity of echocardiography in detecting left ventricular mural thrombosis.

Aged↗

PubMed1997

[Use of abciximab during coronary angioplasty].

The IIb-IIIa glycoprotein is the platelet receptor of fibrinogen and the final common pathway of platelet activation and aggregation. Abciximab is a Fab fragment of the chimeric monoclonal antibody (c7E3) interfering with the glycoprotein receptor. It is the only anti IIb-IIIa currently available, commercialized under the name of Reopro. Preliminary clinical data has been obtained with its use in high risk coronary angioplasty. The EPIC trial showed a 35% relative reduction of the principal combined criterion of judgement of cardiac morbidity and mortality at 1 month, a benefit even greater in acute coronary syndromes (-72%) than in programmed procedures for complex type C lesions (-10%). The incidence of severe bleeding was high (14%). The results of the CAPTURE trial could widen the indications of abciximab to include the period surrounding angioplasty for unstable angina as the use of Reopro in the 24 hours before the procedure significantly reduced the risk of ischaemic events (10.8% versus 16.4%). In programmed angioplasty, the EPILOG trial investigated the effects of adapting the dose of heparin and an infusion of abciximab to body weight early (4th to 6th hour) withdrawal of the arterial introducer without continuing heparin. Using a 70 IU/Kg dosage modulated to algorithms taking into account the ACT, the incidence of bleeding complications was reduced to 1.8%, the same as the control group, and the benefits with regards to ischaemic events were not only maintained but increased (a 56% reduction at 1 months). Utilization of abciximab would be supported by the Cost saving approach of the EPIC trial 3-years follow-up which showed presentation of the initial benefits.

Abciximab↗

PubMed1993

Effects of ultrasound energy on thrombi in vitro.

Ultrasonic energy may be used for dissolution of venous or arterial thrombi. However, its effects may depend on the mode of ultrasonic vibration and on the length of the probe. We investigated the in vitro effects of an ultrasonic angioplasty device coupled with a 130 cm-long flexible titanium probe, with an incorporated automatic optimal frequency of resonance scanning function and continuous mode of emission. Sixteen clots were treated of which eight were whole blood and eight cell-free. In each of these groups, four were treated in association with streptokinase and four by ultrasound alone. The ages of the clots in these subgroups of four were 1, 3, 7, and 15 days. All thrombi were dissolved in 6 min or less (3'15" +/- 1'35") at a mean optimal frequency of resonance of 19,444 Hz. Ninety-six percent of the debris were less than 10 mu. Fewer than 1% of the particulates were larger than 100 mu. These large particulates were observed in disrupted whole blood clots and were almost non-existent in disrupted cell-free clots. They were very fragile. Clot dissolution was not speeded by adding streptokinase to ultrasound. Ultrasound did not induce D-Dimer production, and its effect was most likely to be due to cavitation. Ultrasound energy could represent an advance for thrombotic vascular occlusion therapy, provided that more flexible probes can be devised.

Angioplasty↗

PubMed1993

Effects of ultrasound energy on total peripheral artery occlusions: initial angiographic and angioscopic results.

Ultrasonic energy has been shown to ablate atherosclerotic plaques and arterial and venous thrombi. We used an ultrasonic angioplasty device developed by our group in ten patients with totally occluded femoral artery during surgical bypass. Ultrasonic angioplasty was performed with a 130-cm long and 0.8-cm diameter titanium probe with a 2- or 2.5-mm titanium ball-tip. In one patient, angioplasty could not be performed. Angiographic and angioscopic examination were performed before and after angioplasty in nine patients. Before ultrasound recanalization, angioscopic examination showed that the proximal end of the occlusion was formed by atheromatous material in 3 cases, red thrombus in 3 cases, amd white thrombus in 3 cases. After ultrasound recanalization, angioscopy showed residual stenosis at the site of entry in only one case. In three other cases, the artery was free of residual stenosis without persistent clot. In the five other patients, a residual stenosis was present beyond the proximal occlusion point with some fibrin mesh and small clots. At angiography, flow was restored in 4 cases; in 4 patients flow rate of entry was slow in the distal segment; and in 1 patient, the distal arterial bed could not be opacified. Altogether, ultrasonic angioplasty was able to recanalize a complete occlusion in nine out of ten patients, with partial or complete dissolution of clots and with no complication. At its present stage of development, adjunctive balloon angioplasty would be needed in most cases to obtain unrestricted flow and unsignificant residual stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1993

[Catecholamine induced ventricular tachycardia: a cause of severe syncope during adolescence].

A 15-year-old female teenager had recurrent syncopes and had been unsuccessfully treated for 6 years for seizures and hysteria. Syncopes were always triggered by emotions, or efforts, but electrocardiograms were normal between the episodes. A 24-hour-monitoring during a syncope, and provocative tests (exercise testing and isoprenaline administration) showed severe ventricular arrhythmias with premature polymorphous beats, followed by ventricular tachycardia and then ventricular fibrillation. These "catecholamine-induced" ventricular tachycardias are very rare but are always fatal without treatment. Syncopes are stress-induced and the diagnosis is almost always delayed, because the patients have a normal electrocardiogram, with normal QT interval. The arrhythmia appears beyond a "threshold" sinus rate and is easily reproducible by exercise testing. Betablockers are the only efficient treatment to prevent sudden death.

Adolescent↗